The representatives have committed to remaining engaged in an ongoing talks process, but Unite confirmed it still plans to officially serve industrial action notice on Friday afternoon.

Unite official Richie Browne warned the action will go ahead from December 16 if a resolution over the pension row is not reached.

"Today's meeting between the ESB group of unions and senior management in the ESB began a process of dialogue," Mr Browne said.

"However, Unite considers that insufficient progress was made to defer serving notice if industrial action on the company. Unite will, therefore, be serving notice on the ESB at 2pm tomorrow.

"Notwithstanding this, we will remain fully engaged in the process which began today and, together with the other unions involved, will be focusing all our efforts on resolving this dispute before December 16."

Unite was joined by the Technical Engineering and Electrical Union, Siptu, the Union of Construction Allied Trades and Technicians and the Energy Services Union at the meeting with ESB chiefs today.

In a statement, ESB said there had been "an open and frank exchange of views and significant differences remain between the parties".

It added: "Both parties have agreed to engage in intensive dialogue focused on addressing these differences."

The pensions row centres on claims by the unions over the level of a deficit and also over the company switching retirement plans from defined benefit to contribution, meaning workers are not guaranteed a certain level of payment.

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